05000286/LER-2003-002
| Indian Point Unit 3 | |
| Event date: | 04-29-2003 |
|---|---|
| Report date: | 06-25-2003 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 2862003002R00 - NRC Website | |
DESCRIPTION OF EVENT
- Note: The Energy Industry Identification System Codes are identified within brackets {}.
On April 29, 2003, at 0303 hours0.00351 days <br />0.0842 hours <br />5.009921e-4 weeks <br />1.152915e-4 months <br />, during power escalation from refueling outage 3R12, with reactor Nell power at 59%, a nuclear plant operator discovered a fire at the south end of the high-pressure turbine {TRB} located at 53 ft. elevation of the Turbine Building {NM}. Control Room was notified and Operations manually tripped the reactor. Firefighting foam and permanently installed CO2 system were used to put the fire out. A Notice of Unusual Event (NUE) was declared at 0313 hours0.00362 days <br />0.0869 hours <br />5.175265e-4 weeks <br />1.190965e-4 months <br /> due to the fire exceeding 15 minutes. The fire was extinguished in approximately 15 minutes and declared out approximately 30 minutes later following verification of no reflash. The NUE was terminated at 0521 hours0.00603 days <br />0.145 hours <br />8.614418e-4 weeks <br />1.982405e-4 months <br />. A one-hour notification for the fire (Event # 39807) and a four-hour notification (Event # 39808) for the reactor trip were made to the NRC and a post trip evaluation report 03-03 was completed. No damage to any equipment or personal injury occurred and no Engineered Safety Feature (ESF) actuation was required as a result of the manual reactor trip. During the shutdown, letdown flow automatically isolated due to pressurizer low level. The cause of the isolation was a reduction in the reactor coolant temperature due to auxiliary feedwater flow coupled with a low amount of decay heat, since the unit had just finished a refueling outage. The in-service charging pump was placed in manual, auxiliary feedwater flow was adjusted and pressurizer level and letdown were restored.
The fire was caused by the heat of the turbine casing igniting lubricating oil that had leaked and soaked several of the high-pressure turbine insulating pads. The oil leak was from an improperly installed oil deflector for turbine bearing no. 2. The oil deflector leaked because it was assembled with a gasket on the bottom half and no gasket on the top half. Oil had leaked out of the west side of the deflector at the upper half vertical joint. In April 2003, during refueling outage 3R12, the 31 low-pressure turbine was overhauled. The upper half of the deflector was removed for cleaning and to verify closure of the bearing standard horizontal joint. When the upper half was reinstalled on the lower half, no gasket was installed and Permatex sealant was used on the joint. The thickness of the gasket on the bottom half along with the tightness of the dowels, caused a segment of the oil deflector on the west side of the upper half to be away from the bearing standard and a leak path was created. As part of the immediate corrective actions, the deflector was repaired, a complete inspection of the turbine insulation was performed and all insulation pads that contained oil were replaced with new pads. As an extent of condition review, the entire main turbine and the boiler feed pump turbines were inspected for possible oil leaks and assembly problems.
Upon completion of immediate corrective actions and the extent of condition review, the unit was placed on line at 0736 hours0.00852 days <br />0.204 hours <br />0.00122 weeks <br />2.80048e-4 months <br /> on April 30, 2003. This event was entered into the Entergy Corrective Action Program under CR-IP3-2003-2795.
CAUSE OF EVENT
The cause of the manual reactor trip was operator response to a fire at the south end of the high-pressure turbine. The fire was caused by oil soaked insulation in close contact with a hot turbine casing. The insulation became oil soaked due to a leak on the no. 2 bearing oil deflector. The oil deflector was improperly assembled with a gasket on the bottom half and no gasket on the top half. The cause of the event was human error. Oversight and monitoring by supervision was inadequate and quality standards were not sufficiently enforced which resulted in improper installation of the oil deflector. A contributing cause for this event was poor job planning.
CORRECTIVE ACTIONS
The following corrective actions have been or will be performed under the Corrective Action Plan (CAP) to address the causes of this event and prevent recurrence.
The immediate corrective action was to repair the leaking oil deflector and inspect the entire main turbine and the boiler feed pump turbines for oil leaks or any insulation containing oil. A long-term corrective action plan has been developed to prevent recurrence of this event. All corrective actions arising from this plan have been entered in the Corrective Action Program with scheduled due dates for completion. The plan will address: early planning of turbine projects including milestone schedules, contractor's work scope and procedural requirements, and Quality Assurance Organization involvement. Additionally, procedures for turbine work will be revised to be more specific concerning the closure of gasketed or sealant-applied joints.
EVENT REPORTING
This event is reportable under 10 CFR 50.73 (a) (2) (iv) (A). The licensee shall report any event or condition that resulted in manual or automatic actuation of any of the systems listed in 10 CFR 50.73 (a) (2) (iv) (B). Systems to which the requirements of 10 CFR 50.73 (a) (2) (iv) (A) apply includes the Reactor Protection System (RPS) including reactor scram or reactor trip. This event meets the reporting criteria because the reactor was manually tripped. An emergency one-hour notification per 10 CFR 50.72 (a)(1)(i) was made to the NRC on April 29, 2003 (Event # 39807) for Declaration of Unusual Event due to turbine fire exceeding 15 minutes and a four-hour notification was made to the NRC (Event # 39808) for the reactor trip.
PAST SIMILAR EVENTS
A review of previous Licensee Event Reports (LER) in the past three years did not indicate any similar reportable event. However an event similar to this one, though not reportable, occurred at Indian Point 3 on December 7, 2002 on the 32 main boiler feed pump. During this event, the vapor extractor for the boiler feed pump turbine was out of service and there was oil leakage out of the turbine bearing that allowed oil to soak into the insulation that caught fire. The fire was put out within minutes of discovery and did not jeopardize the operability of the main boiler feed pump. This event was recorded under CR-IP3-2002-04836.
EVENT SAFETY SIGNIFICANCE
This event had no significant effect on the health and safety of the public. There were no actual safety consequences for the event because the event was an uncomplicated reactor trip. There was no Engineered Safety Feature actuation as a result of the manual reactor trip. All the safety systems were in normal status and there were no LCOs, maintenance, testing or surveillances in effect. The RCS pressure remained above the setpoint for automatic SI actuation and the RCS pressure remained below the setpoint for pressurizer PORV or Code safety valve actuation. During the shutdown, letdown flow automatically isolated due to pressurizer low level. The cause of the isolation was a reduction in the reactor coolant temperature due to auxiliary feedwater flow coupled with a low amount of decay heat, since the unit had just finished a refueling outage. The in-service charging pump was placed in manual, auxiliary feedwater flow was adjusted and pressurizer level and letdown were restored. The fire was well within the capabilities of the plant fire suppression systems and the plant fire brigade. The foam hose line and the CO2 system were used to put the fire out. A Notice of Unusual Event (NUE) was declared at 0313 hours0.00362 days <br />0.0869 hours <br />5.175265e-4 weeks <br />1.190965e-4 months <br /> due to the fire exceeding 15 minutes. The fire was extinguished in approximately 15 minutes and declared out approximately 30 minutes later following verification of no reflash. The NUE was terminated at 0521 hours0.00603 days <br />0.145 hours <br />8.614418e-4 weeks <br />1.982405e-4 months <br />.